We have a common sense policy that one of the Sergeants described as "do what your mom taught you"...if it's cold, dress for the weather, if it's warm, dress for the weather. Sleeve length is officer's choice, turtleneck or tie is OPTIONAL with longsleeves (optional as in you can go plain 'ol open collar with a t-shirt if you want). Pretty relaxed.
"Logic is rarely the engine that propels a police department forward."
-David Simon in "Homicide"